Refining of fatty acid esters and fatty acids



. color.

from one or more of such disadvantages as in-,

Patented Nov. 23, 1943 REFINING OF FATTY ACID ESTERS AND FATTY ACIDSWilliam N. Traylor, Hattiesburg, Miss., assignor V to Hercules PowderCompany, 'Wilmington, Del., a corporation of Delaware No Drawing.Application April 18, [1941, Serial'No. 389,174

8 Claims. (01. 260-424) This invention relates to fatty acid esters andfatty acids and more particularly to a process for refining suchmaterials.

Fatty acid esters and fatty acids have been refined by many methods inorder to improve their However, such processes generally suffer volvinga substantial loss of refined product or of changing desirableproperties of the fatty materials treated, or of requiring excessiveprocessing equipment and materials, or of improving the color to only aslight degree. Such disadvantages are encountered for example whentreating fatty acid esters and fatty acids by adsorption or extractionmethods whereby a considerable loss, of yield of refined material isobtained, or by=treating with strong reagents such as concentratedsulfuric acid, thereby destroying considerable fatty materials, or byhydrogenation, oxidation or chlorination which may-involve not onlychange in properties, but loss in yield or use of expensive equipment.

It is an object of this invention to provide an improved process forrefining fatty acid esters and fatty acids.

It is a further object of this invention to provide an improved processfor refining fatty acid esters and fatty acids, which is extremelysimple and economical.

.It is a further object of this invention'to provide an improved processfor refining fatty acid esters and fatty acids in which the yield ofrefinedfatty acid esters or fattyacids based on the material treated issubstantially quantitative.

A still further objectof this invention is to provide a process whichwill effect a substantial improvement in the color of the treated fattyacid esters or fatty acids without substantially tion the treatment maybe carried out on the fatty acid esters or fatty acids in the moltencondition or on these materials dissolved in a suitable, solvent. Afterthe treatment is completed, I

the fatty acid esters or fatty acids or their solution may be washed toremove any water soluble material, and filtered to remove any suspendedmatter. If desired, the solution may be filtered prior to the waterwashing step. In the case of treatment of the fatty acid esters or fattyacids in solution, the fatty acid esters or fatty acids of improvedcolor may then be recovered by evaporation of the solution.

The fatty acid esters and fatty acids which may be refined according tothe process of this invention are the fatty acid esters such asvegetable and animal oils, fats and waxes, and the fatty acids which maybe derived'from them. Examples of such materials are vegetable oils suchastung oil, linseed oil, cottonseed oil, palm oil, etc., or animal oilssuch as bone oil, whale oil, beef tallow, etc., fish oils, such asmenhaden oil,

sardine oil, etc.,' waxes such as sperm oil, beeswax,

affecting the other properties of these substances.

Other objects of this invention will appear hereinafter.

The objects of the invention are accomplished broadly by treating theunrefined fatty acid esters or fatty acids under ionizing conditionswith a metal above hydrogen in the electromotive series and an acidsalt. The treatment is carried out under conditions which will provideintimate contact between the fatty acid esters. or fatty acids and theacid salt and the metal. As a result, the color of thefatty acidestersor'fatty acids is substantially lightened. with practically' no loss inyield and no perceptible effect on the" properties of the materialstreated other than color.

In accordance with the process of thisinven carnauba wax, montan wax,etc.; and fatty acidssuchas commercial oleic acid, fatty acid soapstocks, and fatty acids derived from any of the above fats, oils andwaxes.

The process of this invention is especially valuable when applied to theunsaturated or drying type fatty acid esters'and fatty acids such as,for example tung oil, linseed oil, menhaden oil, oleic acid, linseed oilfatty acids, etc. In the case of treating of such drying type fatty acidesters and fatty acids, the advantage of the'process of this invention,of having no perceptible effect on the physical properties of the acidesters and fatty acids other than color is especially marked since otherprocesses'of refining generally appreciably alterthose properties inlightening the color.

As-solvents for the fatty acid esters and fatty acids when the treatmentis carried out on the fatty acid esters and fatty acids in solution, anysolvent for these materials may be employed which is itself inert in thetreatment. Among such solvents are, for example, monocyclic aromatichydrocarbons such as benzene, toluene, xylene, -etc.; petroleumhydrocarbons such as gasoline, V. M. and P. naphtha, hexane, heptane,etc.; hydrogenated petroleum hydrocarbons. such as those known in thetrade as Solvesso solvents: turpentine, terpenes, and solvents such asethylene dichloride, carbon tetrachloride, cyclohexane, methylcyclohexane, P menthane, tetrahydro and decahydronaphthalenes, isopropylether ,dichloroethyl ether, etc. Where sorted to.

the treatment is carried out on' the fatty acid esters or fatty acids insolution, the concentration of the fatty acid esters or fatty acids insolution is not critical and may be selected to provide adequateworkability of the solution. In general, a concentration within therange of about to 75% by weight may be used, but

preferably the.concentration is' held within the range-of 30% to 60% byweight.

The acid salts which may be used in the process of this invention arethose which contain one or more replaceable hydrogen atoms, such as, forexample, sodium acid sulfate, potassium acid sulfate, monosodium acidphosphate, disodium acid phosphate, monopotassium acid phosphate,

7 dipotassium acid phosphate, calcium acid phosway limiting on theprocess, and the equipment employed will generally determine the maximumpressure which is practical.

The time of treatment of the fatty acid esters or fatty acids may bevaried to produce the result desired. The time necessary to providesatisfactory refining will depend on such factors as the amount of colorbodies present in the material refined. the temperature of thetreatment, the amount of acid salt employed, and other factors. possibleto state any definite time necessaryexcept in relation to a given set ofconditions.

' Under usual conditions reaction time between In order to produce thenecessary refining action, the metal and acid salt should be contactedduring the refining process under ionizing conditions. By ionizingconditions is meant conditions under which the acid salt and metal maydissociate, as in the presence of an ionizing solvent such as water. Itis, therefore, desirable that at least a small amount of water or ofsome other ionizing solvent be present in order that such ionizingconditions are realized. Thus, the acid salt. may be used in the form ofa hydrate if it forms one, or in the form of an aqueous solution. Sodiumacid sulfate in the form of its monohydrate is particularly desirable.Alternatively a small amount of water or other ionizing solvent may beadded. An aqueous solution containing from about 20% of the acid salt toa saturated solution of the salt at the temperature employed may beused.

-It will be understood that the acid salt and the metal above hydrogenin the electromotive series are both in contact with the fatty acidesters or fatty acids during the treatment. To provide satisfactorycontact of the acid salt and metal with the fatty acid esters or fattyacids, itwill be desirable to employ vigorous agitation,

I since the refining action will be appreciably accelerated thereby.

'The'speed with which the fatty acid esters or fatty acids becomerefined is also dependent on the temperature employed in the treatment.While the treatment may be carried out at room temperature, the rate ofrefining is slow for practical purposes. It is preferable to carry outthe treatment at elevated temperatureaand temperatures as high as 200 C.have been found to be satisfactory, although even higher temperaturesare possible. A temperature within the range of about 70 C. to about 125C. is preferable.

When carrying out the treatment of the fatty acid esters or fatty acidsin solution it is convenient to operate at the reflux temperature of thesolvent. When the treatment is to be carried out above the normalboiling point of the solvent, use of superatmospheric pressure is re-The pressures employed are in no about 10 minutes and 5 hours may besatisfactory, although depending on specific conditions, longer orshorter contact times are entirely possible.

' The amount of acid salt used may vary over a wide range depending onfactors such as the particular acid salt used, the degree of refiningdesired, the particular conditions of treatment, as well as otherfactors. Considering the acid salt on an anhydrous basis, for example,ratios of fatty acid esters or fatty acids to acid salt of as high as 40to 1 on a weight basis are prac-' tical. In general, however, ratiosvarying between 10 of fatty acid esters or fatty acid to 1 of acid salt,down to 1 of fatty acid ester or fatty acid to 1 or more of acid saltare desirable. A preferred ratio is approximately 3 of fatty acid estersor fatty acids to 1 of acid salt.

The amount of metal above hydrogen in the electromotive series used isnot particularly critical. It will be desirable, however, to have anamount of such metal present which will be an excess over thetheoretical amount required to react with the acid salt present.

The process of refining fatty acid esters or fatty acids in accordancewith this invention may also be carried out as a continuous process ifdesired. Thus, for example, a solution of the fatty material may betreated with the metal above hydrogen in the electromotive series and anacid salt ina suitable vessel while additional fatty acid esters orfatty acid solution is fed As illustrative of the improved process ofrefining fatty acid esters or fatty acids in accordance with thisinvention, the examples below are cited as typical of the variousembodiments. The colors shown are the colors corresponding to grades ofthe Standard U. S. rosin type.

Example 1 Seventy-five parts by weight of a, commercial Red Oil or oleicacid was dissolved in 310 parts by weight of benzene. This solution wasrefluxed for 1 hour with 15 parts by weight of zinc powder and 23 gramsof sodium acid sulfate monohydrate. The treated solution was filtered toremove suspended matter, water washed, and the solvent removed from therefined oil by vacuum distillation. The color of the oil was improvedfrom an 1+ to a WG grade.

For this reason it is im- The iodine number of the on was substantiallyunchanged.

Example 2 The experiment of Example 1 was duplicated with tun'g oil ofcolor grade N+. The oil was refined to a W grade.

Example 3 Sixty parts by weight of menhaden oil was dissolved in 180parts by weight of benzene and refluxed for one hour with 25 parts byweight of zinc powder and 40 parts by weight of sodium acid sulfatemonohydrate. The benzene solution was decanted, water washed and thesolvent removed from the refined oil by vacuum distillation. The colorof the oil was-improved from a G+ to an M grade.

Example 4- Sixty parts by weight of menhaden oil was heated to 95 C'.with 20 parts by weight of zinc and 60 parts by weight of a 50% aqueousmonosodium acid phosphate solution. The mixture was maintained at thistemperature for 45 minutes under constant agitation. The oil was sep-'arated from the treating solutiornfiltered and water washed. The colorof the oil was improved from a (3+ to a K grade.

Example 5 .25 g. zinc powder and 40 g. NaI-ISOdhO was What I claim anddesire to protect by Letters Patent is:

l. The process of refining a material selected from the group consistingof fatty acid esters and fatty acids which consists of treating saidmaterial under ionizing conditions with a metal above hydrogen in the anacid salt.

2. The process of refining a material selected from the groupconslsting'of drying type fatty acid esters and drying type fatty acidswhich consists of treating said material under ionizing conditions witha metal above hydrogen in the electromotive series and an acid salt.

3. The process of refining a material selected from the group consistingof fatty acid esters and fatty acids which consists of treating saidmaterial under ionizing conditions with a metal added to a solution of100 g. carnauba wax in V 400 g. ethylene dichloride, and the mixturerefluxed for -1 hour with agitation. The solution was decanted from thebleaching agent while hot,

vacuo distfllation left a substantially quantitative yield of bleachedwax which was substantiallylighter in color than the, original (fromdark brown to light brown).

Example 6 A refining treatment was carried out exactly 7 as in Example5, except the wax refined was montan wax. The refined material wassubstantially lighter than the original (from black gray to gray).Because of the opacity of the original and bleached waxes, an accuratecolor could not be obtained.

It will also be understood that the details and examples hereinbeforeset forth are illustrative only and that the invention as broadlydescribed and claimed is in no way limited thereby.

.and water washed. Evaporation of solvent by i ditions with sodium acidsulfate monohydrate .perature within the range of about to about 6. Theprocess of refining linseed oil which consists of treating said linseedoil under ionizing conditions with-sodium acid sulfate mono hydrateancfzinc at a temperature within the range of about 70 to about 125 C.

7. The process of.refining tuna oil which consists or treating said tun:oil under ionizing conand zinc at a temperature within the range ofabout 70 to about 125 C.

8. The process of refining menhaden oil which consists of treating saidmenhaden oil under ionizing'conditions with sodium acid sulfatemonohydrate and aim: at a temperature within the range of about 70 toabout 125' 0.

w. N. mama.

electromotive series and

